Protein E (PE) is an outer membrane lipoprotein with adhesive properties. It plays a role in the adhesion/invasion of non-typeable Haemophilus influenzae (NTHi) to epithelial cells. (J. Immunology 183: 2593-2601 (2009); The Journal of Infectious Diseases 199:522-531 (2009), Microbes and Infection 10:87-96 (2008)). It is highly conserved in both encapsulated Haemophilus influenzae and non-typeable H. influenzae and has a conserved epithelial binding domain. (The Journal of Infectious Diseases 201:414-419 (2010)). Thirteen different point mutations have been described in different Haemophilus species when compared with Haemophilus influenzae Rd as a reference strain. Its expression is observed on both logarithmic growing and stationary phase bacteria. (WO2007/084053).
Protein E is also involved in human complement resistance through binding vitronectin. (Immunology 183: 2593-2601 (2009)). PE, by the binding domain PKRYARSVRQ YKILNCANYH LTQVR (SEQ ID NO. 1, corresponding to amino acids 84-108 of SEC) ID NO. 4), binds vitronectin which is an important inhibitor of the terminal complement pathway. (J. Immunology 183:2593-2601 (2009)).
Pilin A (PilA) is likely the major pilin subunit of H. influenzae Type IV Pilus (Tfp) involved in twitching motility (Infection and Immunity, 73: 1635-1643 (2005)). NTHi PilA is a conserved adhesin expressed in vivo. It has been shown to be involved in NTHi adherence, colonization and biofilm formation. (Molecular Microbiology 65: 1288-1299 (2007)).
Non-typeable Haemophilus influenzae is an important and common respiratory pathogen that causes otitis media in infants and children. NTHi is, after Streptococcus pneumoniae, the most common cause of acute otitis media in children (J. Immunology 183: 2593-2601 (2009), Pediatrics 113:1451-1465 (2004)). It is an important cause of sinusitis in children and adults. (Current Infectious Disease Reports 11:177-182 (2009)). It has been associated with increased risk of exacerbations in chronic obstructive pulmonary disease (COPD) in adults. (Journal of Chronic Obstructive Pulmonary Disease 3:109-115 (2006)). In addition, non-typeable H. influenzae causes community-acquired pneumonia in adults and may cause pneumonia in children in developing countries. (Current Infectious Disease Reports 11:177-182 (2009)).
A need for vaccines for NTHi exists.